Motor control



April 15, 1924. 1,490,776

B. W. JONES MOTOR CONTROL Filed March 29. 1922 Im/entr: Benjamin \M Jones,

WWQ

His Attorney Patented Apr. 15, 1924.

UNITED STATES 1,490,71 PATENT oFF cE.

BENJAMIN W. JONES, OESCHENECTLDY, NEW YORK, ASSIGNOR T0 GRIT-EAL W0 I COIPANY, A CORPORATION OF NEW YORK.

IOTOB CONTROL.

Application am Inch 20, 1922. Serial in). 541,704.

.To all whom it may concern: I

Be it known that I, BENJAMIN W. Joints, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Motor Control, of which the following is a specification.

My invention relates to the control of.

electric motors, and it provides improved means whereby the motors may be started and stopped and generally controlled in a safe, reliable and eflicient manner- One of the objects of the invention is toprovides a good solution. The material to e formed into a metallic tube is projected through a tube-forming die for a short distance so thatthe end of the tube may be grasped by tongs operated by an electric motor and the tube drawn through the die by the motor at comparatively high speed.

If the motor is operated at high speed continuously, when the tongs first engage the end of the tube,.the speed may be such as to pull the tongs loose from the tum or give a jerk to the tube which will uce objectionable results, or produce ot er undesirable etfects as'will be understood by those skilled in the art. It is desirable that t the motor operate at a comparatively slow s until the tongs safely and securely grab the end of the tube and that the speed of the motor be gradually increased up to the full operating speed in as short an'interval of time as is practical, so that the tube may be drawn through the die at a comparatively high speed.. Furthermore, it is desirable that the speed of the driving motor at the start of operation shall be such that the metal may begin to flow. The

, speed of operation may be considerably introlled in a simple, reliable and effective manner, so that the speed of the motor is in accordance with the momentary requirements.

For a better understanding of the invention, reference is had to the accom anying drawing which shows in simplified iagram a system of motor control embodying the invention for the purpose of explaining the principles thereof.

The electric motor 10 is provided with a shunt field 11, and a resistor 12 is provided for controllin the degree of excitation of the shunt fielzf motor. In order to ex lain theprinciples of the invention, it Wll be assumed that the motor 10 is used to operate or drive a tube-drawing machine, and it will be un-' derstood that the rotating element of this motor may be mechanically connected to drive the tube-drawing machine in any suit able manner. The resistors 13 and 14 are provided for limiting the current taken by the motor at starting and during the pump back caused by suddenly increasing the field excitation of the motor when the motor of the series lockout t pe is provided for short circuiting the resistor 14 and thereby connecting the motor armature directly across the source of supply 17. 'These electromagnetic switches 15 and 16 are prefer- .ably of the eta'pe having each a series windresponsively to the motor aring energiz mature current and a shunt winding energized to cooperate with the series winding to control a movable switch member. These switches are preferably of the type described and broadly claimed in the Patent No. 1,445,994, dated Februar 20, 1923, 'issued to Eugene R. Caricho and myself,- althou h the invention is not necessarily limited 'to the use of this particular type of switch for controlling the accelerating 're-. sistors 13 and 14. This application is assi ed to the same assignee as the said Canchoff and Jones patent.

The resistor 12 in the shunt field circuit of the drivin motor is controlled by a normally open. e ectromagnetic switch 18, and this switch 18 is controlled by the normally closed electromagnetic relay 19 and the auxiliary switch 16' of the accelerating contactor 16. This relay 19 is referably of the type described and broad y claimed in the said Carichofi and Jones patent. The relay comprises a series winding 20 which is connected in the motor armature circuit and therefore ener ized responsively to the current taken by e motor, and the shunt winding 21 of this relay is controlled responsively to the operation of the electromagnetic switch 18; that is, the winding 21 is energized when the switch 18 is closed and deenergized when the switch 18 is opened.

The relay is provided with a magnetic movable member 22 which is under the control of the windings 20 and 21, and a switch member 23 is connected to and operated by the plunger 22. This switch member 23 is biased to the closed sition as shown so as to energize the win ing of the electromagnetic switch 18. The arrangement is such that switch member 23 is operated to the open position so as to cause the electromagnetic switch 18 to open and insert the resistor 12 in the motor armature field circuit when the current taken by the motor has increased to a predetermined value. When the switch 18 opens, the shunt winding 21 of the relay 19 is opened at the auxiliary switch 24, so that the return of the switch member 23 to its biased position is under the control of the series winding 20. The relay will thereby be operated to close and energize the switch 18 to short circuit the resistor 12 when the current taken by the motor subsequently drops to a predetermined value, which may be different from the value of the motor armature current at which the Switch member 23 is operated to the open position.

As thus constructed and arranged, the operation of my invention is briefly as follows: The pilot or master switch 25 will first be closed, thereby energizing the electromagnetic line contactor 26 to close and connect the motor armature to the source of supply through a circuit which includes the starting or accelerating resistors 13 and 1 1. This circuit may be traced as follows: from the line contactor 26, through the series winding of the relay 19, the resistor 14, the series winding of the contactor 15, resistor 13, through the motor armature to the other supply conductor. The auxiliary switch 16 associated with the accelerating contactor 16 is normally biased so as to make engagement with its stationary contact. so that the winding of the electromagnetic switch 18 is energized through a circuit which includes the series winding 20 of the relay l9, resistor 14, series winding of cont-actor 15. resistor 13, series winding of contactor 16. main switch member of contactor 16. the auxiliary switch 16' to the other supply conductor. It will he noted that when the auxiliary switch 16 is in its biased position, the electromagnetic switch 18 is energized to close, regardless of the operation of the relay 19 so that the motor will start on full field. The shunt winding 28 of the accelerating contactor 15 is energized through the auxiliary switch 29 of the line contactor 26 when this line contactor closes. When the current taken by the motor drops to a predetermined value, the accelerating contactor 15 will operate to short circuit the starting resistor 13 and automatically include the series winding of the contactor 16 in the motor armature circuit. The contactor 15 in closing operates the auxiliary switch 27 against its bias so as to make engagement with its stationar contact and thereby energize the shunt winding 30 for the contactor 16. \Vhen the motor current again drops to a predetermined value, this contactor 16 will be energized to close and short circuit the resistor 14, thereby connecting the motor armature directly across the source of supply. The auxiliary switch 16' is opened by the closing of the accelerating contactor 16, but the field contactor 18 will be maintained closed through the contacts of the relay 19. The accelerating contactors 15 and 16 will be maintained in their closed positions by their respective shunt coils 28 and 30, and their series coils.

Assume that the equipment has been thus started and that the motor is used to operate a tube-drawing machine. By reason of the fact that the resistor 12 in the shunt field winding of the motor is short eircuited, the motor is 0 rating at its basic or slowest speed. W en the tube to be drawn is inserted through the die by the operator so that the tongs of the tube-drawing machine may engage the end of the tube to draw the tube through the die, the current taken by the motor will inciease to such a value when the tube is grasped by the tongs that the cooperating shunt and series windings of the relay 19 will cause the switch member 23 of the relay to be operated to the open position, thereby deenergizing the electromagnetic switch 18. (It will be remembered that the auxiliary switch 16' of the starting contactor 16 opened its circuit for the energization of the winding of the contactor 1.8 when the contactor 16 closed and that the winding circuit of this contactor was maintained through the contacts of the relay 19). The electromagnetic switch 18 thereby opens and inserts the resistor 12 in the circuit of the shunt field 11. This will cause the speed of the driving motor to gradually increase and thereby cause the tube to be drawn through the die at a comparatively high speed. The opening of the electromagnetic switch 18 decucrgixcs the shunt windings 21 of the relay 19 at the auxiliary switch 24 so that the return of the switch member 23 of the relay to its biased position at which ries win ie p ih f lir P ew the series; con tac o is under the sole. co rbl 0f "the'sei'i'es'windk the motor 'gwhen a te tt me e e a thesp'eed f the rim that the (i pei gtg 13mm a x creasedi -fi Thecoiitroltof theishu t winding ing of i the" relay. f I When "the tube "lias f 21""0f the: relay-by'the ea uxiliary 2 Switch been drawn through thediefit is desirable bf the;'field eontaeto gil81is positiveg1 thatyis v that the sfpeed" ofth'e' n idto'r' sha llireturh when the ficld contactor isiopemqthe shunt to: the basic s w speed order to ready windinggis deenergizdxand :avhefii the: field pal-mom of tube drawing."contactor asi closedgi-vtheiishunt; ivindingr is v I I drawifthrough thedie, thefiienergised. i' llhatiiinsure's ,a.=.ipositive op current taken' by th'e eleotrie'fnrotor will he tion of the reidy imiiiinsuresutllat :the'iop a-g decreasedibut thisfloiirre'rftj will' be lina'rily tion of the relayswil=lsbei directlymind; j a higher yaliiefthan' thelciirre'tit 't'aken b v ively' govrnedby,the idegreeofy ing'liQhthflthe 'basi'c of 'zh motar filda" "1 r1 w; "ctmnr taken by"tire lti wi ll' l ie'understoo Sk ilylddlli a prdeteriiiined *value;th" "-the *iii tfi that Whilefl 'lmve :deseribedmiy in-lgi '"willbfihagrfetical'ly tip "connection withitsiopeiiation:1015.80 erated tfo'f fits olosed positib t1erehy=ene tiibekdta'wingmiachineibecause otthezfaeh;

t'ch I8 to'shdrt*-that the invention hasa particular-appli-;

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controlling".i'tlieasaid ha ing a -windingw'enerai c irrentfa unt wind 'ganda swfitch meme;

barbie-sea wane positiori under th'e control of said windings, and connections whereby the said switch member isoperated against its bias under the control of both of said 120 windings to reduce the excitation of the said field when the current taken by the said motor rises to a predetermined value and is subsequently operated to its biased position under the control of the series winding to increase the excitation of the said field when the current taken by the motor drops to a predetermined value.

3. A system of motor control comprising an electric motor having a shunt field, an

' ,l. i i' chinenee ay I H o" hefroritrol field of the electric motorandma' d'irectfhis attentionl'entirely ti) hi5 btheij ilti'esin' attend ing the tube-drawing machine; It will also be observed that the excitation of the shunt field of the motor is reduced in response to the operation of the relay 19 with the shunt and series coils of the relay cooperating, and that the excitation of the shunt field is increased by the operation of the relay 19' with the switch member 22 thereof under the sole control of the series winding 19. That permits of calibrating the relay so that the value of motor armature current at which the speed of the motor'is to be increased may be adjusted independently of the value of the motor armature current at speed,

is operated under the control of both of said 1 windings to reduce the excitation of the said field to increase the motor speed, the switch member is operated under the control of the said series winding to increase the excitation of the said field to reduce the motor and both of said windings prevent the operation of the switch member during the generator action of the motor when the excitation of the said field is thus increased.

4-. A system of motor control comprising a variable speed electric motor having a shunt field, a resistor for controlling the said field, an electromagnetic switch of the series lockout type having a series winding in the motor armature circuit and a shunt winding, the said switch having a switch member biased to the closed position to efi'ect the short circuiting of the said resistor, and connections whereby the said switch member is operated to the open position under the control of both windings to efiect the opening of the short circuit around the said resistor when the current taken by the motor rises to a predetermined value and is operated to the closed position under the control of the series winding when the current taken by the motor subsequently drops to a predetermined value.

5. A system of motor control comprising a variable speed electric motor having a shunt field, a series lockout type electromagnetic switch for controlling the said field, the said switch having a series winding in the motor armature circuit, a shunt winding and a switch member biased to one ition under the control of the means for controlling the said shunt winding responsive to the degree of excitation of the said field, and connections whereby the said switch member is operated to reduce the excitation of the said field under the of both of current rises control said windings when the motor to a predetermined value and closing and opening said windings,

is subsequenttr operated to increase the oxcitation of the said field under the control of the said series winding when the motor ('nl'rrnt drops to a predetermined value.

(3. system of motor control comprising a variable speed electric motor having a shunt firhl. a resistor for controlling the said field. an tlti'll()llltl llltll( switch for controlling the said resistor. a relay having a switch member biased to one position for controlling the said switch. the said rela having :1 series winding energized in nccort ance with the motor current and a shunt winding, and connections whereby the shunt winding is energized to cooperate with the said series winding to control the said switch member when the said electromagnetic switch is closed, and is deenergized so that the said switch member is under the control of the said series winding when the said electromagnetic switch is 0 ion.

7. A system of motor contro comprising a variable speed electric motor having a shunt field, a resistor for controlling the said field, a normally open electromagnetic switch for short circniting the said resistor, an electromagnetic relay of the series lockout type having a switch member biased to the closed position to energize the said switch to close, the said relay having a series winding in the motor armature circuit and a shunt winding, means controlled by the said switch for energizing and deenergizing the said shunt winding in res use to the ofthe sai switch, and connections whcreb the said relay switch member is operate to deener 'ze the said switch under the control of bot relay windings when the current taken by the motor rises to'a predetermined value, the switch member is operated to the closed osition to energize the said switch under t e control of the relay series winding when the current taken by the motor subsequently drops to a predetermined value, and the o ning of the relay switch member duri t e aerator action of the motor when t e excitation of the closing the said field is thus increasedely of the said switch is raven In witness whereo I have hereunto so my hand this 28th day of March 1922.

BENJAMIN W. JONES. 

